1. Field of the Invention
The invention relates to a recording device for recording a video stream and a trick-mode data signal on a record carrier, the recording device including:
receiving means for receiving an input signal comprising at least one information signal,
selection means for selecting a first video stream from an information signal,
trick-mode data generating means for deriving a trick-mode data signal,
write means for recording the first video stream in a normal-play area on the record carrier and the trick-mode data signal in trick-mode area on the record carrier.
The invention also relates to a method of recording a video stream and a trick mode data signal on a record carrier.
2. Description of the Related Art
A recording device of the type defined in the opening paragraph, is known from IEEE Transactions on Consumer Electronics, Vol. 41. No. Aug. 3, 1995, xe2x80x9cAn experimental consumer recorder for MPEG-coded video signalsxe2x80x9d. In the known device, one program is selected from a digital information signal, in the form of an MPEG signal, this MPEG signal containing a plurality of programs. The trick-mode data generating means derive a trick-mode data signal from the selected program. The trick-mode data signal is intended for reproduction of the selected program by a reproducing device with a reproducing speed other than, for example, higher than, the normal reproducing speed. A user can then view parts of a program which are of less interest more quickly by means of a trick-mode data signal, and can subsequently view a more interesting part of the program at the normal speed by reproduction of the video stream. The selected program is recorded on a record carrier together with the trick-mode data signal.
It is an object of the invention to provide a device of the type defined in the opening paragraph, which is capable of recording more than one program of the available programs in a manner described hereinbefore.
To this end, a recording device in accordance with the invention is characterized in that
the selection means is further adapted to select at least a second video stream from an information signal,
the trick-mode data generating means are adapted to:
derive trick-mode images associated with each of the selected video streams,
combine the trick-mode images of each of the selected video streams to the trick-mode data signal,
the write means are further adapted to record the at least two selected video streams in the normal-play area on the record carrier.
A recording device having said characteristic features has the advantage that it generates one trick-mode data signal, this trick-mode data signal being recorded in the trick-play area on the record carrier, as is known from the state of the art. The trick-mode data signal in the trick-play area can be read and reproduced by means of a known reproducing device.
It would be possible to generate a separate associated trick-mode data signal for each selected video stream. Each trick-mode data signal should then be recorded in a separate trick-play area. In order to enable the separate trick-mode data signals to be reproduced, a reproducing device should have special provisions enabling the separate trick-play areas to be read in a trick-play mode. Another disadvantage of one trick-mode data signal per selected video stream and, consequently, the number of separate trick-play areas, is that the amount of space required for the trick-mode data signals increases as a linear function of the number of recorded video streams. For each selected video stream, a part of the storage capacity on the record carrier is utilized as trick-play area for the trick-mode data signal associated with said selected video stream. The total storage capacity on the record carrier available for use as normal-play area decreases because the size of the area used for the individual trick-mode data signals increases.
The information signals applied to an input of the recording device together form the input signal. An information signal can be a channel on a cable system or a satellite. If the information signal takes the form of an MPEG program stream or MPEG transport stream, the information signal may contain more than one video stream. A recording device in accordance with the invention is adapted to select at least two video streams. These video streams may originate from different channels or from, for example, one MPEG transport stream. If, for example, three video streams are selected, two video streams may originate from an information signal in the form of an MPEG transport stream, and one video stream may originate from another information signal. In an embodiment of the recording device, in accordance with the invention, the trick-mode images of the selected video streams are combined to one mosaic image. The number of images in the mosaic screen depends on the number of selected video streams.
An embodiment of the recording device, in accordance with the invention, is adapted to reduce the size of the trick-mode images of the images corresponding to the selected video streams. An advantage of reducing the size of the trick-mode images is that the amount of information for the trick-mode images per selected video stream is reduced. When the trick-mode images are reduced in size by a factor which corresponds to the number of selected video streams, the amount of information of the trick-mode data signal will remain substantially the same and will not depend on the number of selected video streams. As a result of this, the trick-mode data signal may be recorded in the trick-play area on the record carrier without the area on the record carrier being extended.
A further embodiment of the recording device, in accordance with the invention, is characterized in that the image-selection means is adapted to generate the trick-mode images from at least some of the I images from each of the selected video streams. The I images in an MPEG signal contain all the information required for generating a video image, in contradistinction to the P and B images in the MPEG signal, which require at least the information from another image, for example, an I image. The use of I images for the generation of trick-mode images has the advantage that the trick-mode images can be further reduced in a comparatively simple manner, for example, by sub-sampling, as a result of which, the reduced trick-mode images of a selected video stream can be arranged at a predetermined location in the mosaic image.
Another embodiment of a recording device, in accordance with the invention, is characterized in that the write means is adapted to record a serial data stream comprising packets of information of the at least two selected video streams in the form of a number of normal-play signals corresponding to the selected number of video streams, and information of the trick-mode data signal in the form of a trick-play signal, respectively, in the normal-play area and in the trick-play area on the record carrier. Since the recording device generates an MPEG-2 output signal, the recorded information, including the trick-mode signal, can be processed by known reproducing devices capable of processing MPEG-2 signals. This has the advantage that the known reproducing device can process the trick-mode data in the same way as the other data streams. No additional means are required for reproducing the trick-mode data in the form of mosaic images.
A method in accordance with the invention is characterized in that the method further comprises the steps of:
selecting at least a second video stream from an information signal,
recording the at least two selected video streams in the normal-play area on the record carrier, and the step of deriving the trick-mode data signal comprises the following sub-steps:
deriving trick-mode images associated with each of the selected video streams,
combining the trick-mode images of each of the selected video streams to the trick-mode data signal.